Soldier Caste Research Articles

<p><strong>New species of termite <em>Pseudocapritermes kunjepu </em>Mathew sp. nov. (Blattodea: Termitidae: Termitinae) from India</strong></p>

The genus Pseudocapritermes Kemner, 1934, endemic to Oriental region is represented by 18 species. A new species, Pseudocapritermes kunjepu Mathew sp. nov. (Isoptera, Termitidae, Termitinae), is described from Kerala, India, based on the characters of soldiers and workers. Morphological measurements of the soldiers and workers are given with suitable illustrations. A revised key to the species of Pseudocapritermes (based on soldier caste) found in India along with the species distribution map are also provided. Key words: Isoptera, new species, Pseudocapritermes, Termitidae

<p><strong>A new nasute-termite <em>Ceylonitermes nivedita </em>sp. nov. (Isoptera: Termitidae) from India along with first record of worker dimorphism </strong></p>

A new nasute termite Ceylonitermes nivedita sp. nov. (Isoptera: Termitidae) is described from the tropical rainforests of Manipur, India. Both the soldier and worker castes of the species are described. The workers are strongly dimorphic and no such dimorphism is reported hitherto among the 3 known species of Ceylonitermes. A revised dichotomous key to identify all the 4 known species of the genus is also provided. The proposed new species is a minor pest of bamboo. Key words: Ceylonitermes, India, Nasutitermitinae, key

Rugitermes tinto: A new termite (Isoptera, Kalotermitidae) from the Andean region of Colombia.

The imago and soldier castes of a new Rugitermes Holmgren, 1911 species, R. tintosp. nov. are described. It is the ninth species of Rugitermes from South America and the first record of this genus from Colombia. Unlike its congeners, the soldier of R. tinto has very dark head capsule pigmentation and acute protuberances projecting from frontolateral ridges.

Tauritermes bandeirai: A new drywood termite (Isoptera, Kalotermitidae) from the Caatinga and Atlantic Forest of Brazil

The imago and soldier castes of a new Tauritermes Krishna, 1961 species, Tauritermes bandeiraisp. nov. are described. It is the fourth species of Tauritermes and occurs from the Caatinga and Atlantic Forest of Brazil. Unlike its congeners, the soldier of T. bandeirai has prominent frontal horns.

Potentiality of Novel Strain of Metarhizium anisopliae (Metarhizium anisopliae Strain DULS TTRA) against Odontotermes obesus, A Pest of Camellia sinensis (L.) O. Kuntze

Odontotermes obesus (Rambur) is an important termite pest of tea of North East India. The current study shows that a novel strain of Metarhizium anisopliae (Metarhizium anisopliae strain DULS TTRA, Accession no. KT 119358) a tea soil fungus is highly pathogenic to both worker and soldier caste of Odontotermes obesus in in-vitro condition. Efficacy of the experimental fungi further assessed by comparing with commercial formulation showed to have less LT50 and LC50 than the established virulent strain. We recommend the strain as a potential bio-control candidate against Odontotermes obesus.

The making of the defensive caste: Physiology, development, and evolution of the soldier differentiation in termites

Termites (Blattodea, Termitoidea, or Isoptera) constitute one of the major lineages of eusocial insects. In termite societies, multiple types of functional individuals, that is, castes, perform divisions of labors to coordinate social behaviors. Among other castes, the soldier caste is distinctive since it is sterile and exclusively specialized into defensive behavior with largely modified morphological features. Therefore, many of the previous studies have been focused on soldiers, in terms of ecology, behavior, and evolution as well as developmental and physiological mechanisms. This article overviews the accumulation of studies especially focusing on the developmental and physiological mechanisms underlying the soldier differentiation in termites. Furthermore, the evolutionary trajectories that have led the acquisition of soldier caste and have diversified the soldier characteristics in association with the social evolution are discussed.

First records of the termite, Termes hispaniolae (Banks, 1918) (Isoptera, Termitidae, Termitinae), from Bolivia and new Caribbean Basin records

The genus Termes Linnaeus, 1758 occurs in the Neotropical, Ethiopian, and Oriental regions and is notable for the long, narrow, and nearly symmetrical mandibles of the soldier caste.  I report the presence of T. hispaniolae (Banks, 1918) in Bolivia and provide many additional new geographic records throughout the Caribbean Basin.  Termes hispaniolae is common in much of its range, and workers are characterized by a diagnostic enteric valve armature that is described here for the first time.

Trait evolution is reversible, repeatable, and decoupled in the soldier caste of turtle ants

The scope of adaptive phenotypic change within a lineage is shaped by how functional traits evolve. Castes are defining functional traits of adaptive phenotypic change in complex insect societies, and caste evolution is expected to be phylogenetically conserved and developmentally constrained at broad phylogenetic scales. Yet how castes evolve at the species level has remained largely unaddressed. Turtle ant soldiers (genus Cephalotes), an iconic example of caste specialization, defend nest entrances by using their elaborately armored heads as living barricades. Across species, soldier morphotype determines entrance specialization and defensive strategy, while head size sets the specific size of defended entrances. Our species-level comparative analyses of morphotype and head size evolution reveal that these key ecomorphological traits are extensively reversible, repeatable, and decoupled within soldiers and between soldier and queen castes. Repeated evolutionary gains and losses of the four morphotypes were reconstructed consistently across multiple analyses. In addition, morphotype did not predict mean head size across the three most common morphotypes, and head size distributions overlapped broadly across all morphotypes. Concordantly, multiple model-fitting approaches suggested that soldier head size evolution is best explained by a process of divergent pulses of change. Finally, while soldier and queen head size were broadly coupled across species, the level of head size disparity between castes was decoupled from both queen head size and soldier morphotype. These findings demonstrate that caste evolution can be highly dynamic at the species level, reshaping our understanding of adaptive morphological change in complex social lineages.

Social trematode parasites increase standing army size in areas of greater invasion threat.

Organisms or societies are resource limited, causing important trade-offs between reproduction and defence. Given such trade-offs, optimal allocation theory predicts that, for animal societies with a soldier caste, allocation to soldiers should reflect local external threats. Although both threat intensity and soldier allocation can vary widely in nature, we currently lack strong evidence that spatial variation in threat can drive the corresponding variation in soldier allocation. The diverse guild of trematode parasites of the California horn snail provides a useful system to address this problem. Several of these species form colonies in their hosts with a reproductive division of labour including a soldier caste. Soldiers are non-reproductive and specialized in defence, attacking and killing invading parasites. We quantified invasion threat and soldier allocation for 168 trematode colonies belonging to six species at 26 sites spread among 10 estuaries in temperate and tropical regions. Spatial variation in invasion threat was matched as predicted by the relative number of soldiers for multiple parasite species. Soldier allocation correlated with invasion threat at fine spatial scales, suggesting that allocation is at least partly inducible. These results may represent the first clear documentation of a spatial correlation between allocation to any type of caste and a biotic selective agent.

Proteomic-components provide insights into the defensive secretion in termite workers of the soldierless genus Ruptitermes

Termite soldiers constitute the defensive frontline of the colonies, despite workers also perform such tasks, especially within the Neotropical Apicotermitinae, in which all species are soldierless. Workers of the genus Ruptitermes display an extreme form of defense, characterized by body rupture and release of a sticky secretion. Previous observations suggested that such behavior may be advantageous against enemies, but the chemical composition of this secretion has been neglected. Here we firstly provide the proteomic profile of the defensive secretion of Ruptitermes reconditus and Ruptitermes pitan workers. Additionally, the mechanisms of action of this behavior was evaluated through different bioassays. A total of 446 proteins were identified in R. reconditus and 391 proteins in R. pitan, which were classified into: toxins, defensins and proteolytic enzymes; sticky components/ alarm communication; proteins related to detoxification processes; proteins involved in folding/conformation and post-translational modifications; housekeeping proteins; and uncharacterized/hypothetical proteins. According to the bioassays, the self-sacrifice is triggered by a physical stimulus, and the defensive secretion may cause immobility and death of the opponents. Assuming that termites are abundant in the tropics and therefore exposed to predators, suicidal behaviors seem to be advantageous, since the loss of an individual benefit the whole colony. SignificanceAlthough recent studies have reported the biochemical composition of different weapons in soldiered species of termites, such efforts had not been applied to sordierless taxa up until now. Thus, this is the first report of the defensive mechanisms in soldierless termite species based on proteomic analysis. The diversity of compounds, which included toxin-like and mucin-like proteins, reflect the mechanisms of action of the defensive secretion released by termite workers, which may cause immobility and death of the opponents. Our findings may contribute to the knowledge regarding the development of defensive strategies in termites, especially in groups which lost the soldier caste during the evolution.

Two new species of an Indian endemic genus Krishnacapritermes Chhotani (Isoptera: Termitidae) from the Kerala part of the Western Ghats, India

ABSTRACT Krishnacapritermes Chhotani (Isoptera: Termitidae) is one of the endemic termite genera from the Western Ghats of India. Under the genus, only two species Krishnacapritermes maitii Chhotani and Krishnacapritermes thakuri Chhotani were known earlier. The present study describes two new species, Krishnacapritermes dineshan Amina and Rajmohana sp. nov. and Krishnacapritermes manikandan Amina and Rajmohana sp. nov. from the higher elevation hill ranges of Western Ghats part of Kerala. DNA barcodes based on cytochrome oxidase I genes were generated for K. thakuri and K. dineshan from multiple locations and tested for phylogenetic relationships. The paper provides a dichotomous key for the four species of Krishnacapritermes and a species distribution map, along with data on the extension of distribution range for K. maitii and K. thakuri. Comments on intracolonial variability of the hyaline lateral points or processes of the labrum in soldier caste are included. Pericapritermes travancorensis Mathew and Ipe syn. nov. is treated as a junior synonym of K. thakuri. http://www.zoobank.org/urn:lsid:zoobank.org:pub:E2F050B5-2F85-415A-A446-4DC7FCDA1068

Screening of reference genes for expression analysis in the study of soldier caste differentiation of Formosan subterranean termite Coptotermes formosanus Shiraki.

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is a serious pest worldwide. Juvenile hormone analog (and its analogs such as methoprene) can induce the transformation of the worker caste into soldier caste in C. formosanus. However, several factors, such as feeding substrate and colony origin, influence the proportion of solider formation. The molecular mechanism of worker to soldier transformation of C. formosanus is still not clear. RT-qPCR is a powerful tool for molecular studies. Accurate gene quantification by the relative quantification method requires a stable expressed gene as the reference gene. However, no reference genes were available for this species in the methoprene bioassay. To study the problem of gene response to methoprene by RT-qPCR we have to first screen reference genes in C. formosanus. Workers were fed with methoprene. Termites were collected during the methoprene bioassay and separated into head and thorax+abdomen. Expression profiles of 10 candidate reference genes in the two body part types were investigated using RT-qPCR. The results were analyzed by a set of established methods (geNorm, NormFinder, BestKeeper, and RefFinder) as well as comparative ΔCt method. Our results suggest that RPS18 is the most stably-expressed gene both in the head and thorax+abdomen for expression analysis in the methoprene bioassay of C. formosanus. The screening of suitable reference genes in C. formosanus establishes the foundation for the molecular study of soldier caste differentiation in this species.

Taxonomy of the genus Longipeditermes Holmgren (Termitidae, Nasutitermitinae) from the Greater Sundas, Southeast Asia

More than 200 colonies of the genusLongipeditermeswere collected in our field surveys across the Sundaland region of Southeast Asia from 1998 to 2014. Two species,L. kistneriAkhtar & Ahmad andL. logipesHolmgren, are recognized and redescribed with color photographs of the workers and major soldiers. We use variation in characters of soldier caste (head capsules, antennae, and pronotum) and worker caste (antennae and mandibles) to distinguish these two species.Longipeditermes kistneriseems to prefer high-altitude forests (above 1,000 m) and has so far been found exclusively in Java and Sumatra, whileL. logipesseems to prefer lowland and swamp forests and is widespread in the Greater Sundas.

Neotermescostaseca: a new termite from the coastal desert of Peru and the redescription of N.chilensis (Isoptera, Kalotermitidae).

The imago and soldier castes of a new Neotermes species, N.costaseca, are described. It is only the third termite species known from the Pacific coastal desert of Peru. Neotermescostasecasp. n. is compared with the allopatric Neotermeschilensis from the arid central and southern coastal plain of Chile.

Characterization of gut bacterial community associated with worker and soldier castes of Globitermes sulphureus Haviland (Blattodea: Termitidae) using 16S rRNA metagenomic

Abstract Globitermes sulphureus is a major pest in coconut plantations and also a secondary pest in the urban, suburban and rural areas of building structures, as well as in tropical agriculture areas. Although the literature revealed microbiome in termite guts, the bacterial community in G. sulphureus intestinal tracts remain largely unidentified. Here, we aimed to characterize the bacterial community associated with the worker and soldier castes of G. sulphureus using 16S metagenomic. The Illumina HiSeq 2500 sequencing machine was used to amplify the V3 and V4 regions of the 16S rRNA gene. The sequencing output was analyzed using Qiime pipeline v1.9.1. The result of the analysis showed that Spirochaetes, Fibrobacteres, Firmicutes, Proteobacteria, and Bacteroidetes were the dominant phyla that reside in the guts of the worker and soldier castes. We found that the worker and soldier castes shared similar bacterial phyla in their guts but different bacterial genera. Our findings provided a baseline information on microbial community inhabiting G. sulphureus guts up to the genus level for some phyla.

Roisinitermesebogoensis gen. & sp. n., an outstanding drywood termite with snapping soldiers from Cameroon (Isoptera, Kalotermitidae).

Termites have developed a wide array of defensive mechanisms. One of them is the mandibulate soldier caste that crushes or pierces their enemies. However, in several lineages of Termitinae, soldiers have long and slender mandibles that cannot bite but, instead, snap and deliver powerful strikes to their opponents. Here, we use morphological and molecular evidence to describe Roisinitermesebogoensis Scheffrahn, gen. & sp. n. from near Mbalmayo, Cameroon. Soldiers of R.ebogoensis are unique among all other kalotermitid soldiers in that they possess snapping mandibles. The imago of R.ebogoensis is also easily distinguished from all other Kalotermitidae by the lack of ocelli. Our study reveals a new case of parallel evolution of snapping mandibles in termites, a complex apparatus responsible of one of the fastest biological acceleration rates measured to date.

Loss of males from mixed-sex societies in termites

BackgroundSexual reproduction is the norm in almost all animal species, and in many advanced animal societies, both males and females participate in social activities. To date, the complete loss of males from advanced social animal lineages has been reported only in ants and honey bees (Hymenoptera), whose workers are always female and whose males display no helping behaviors even in normal sexual species. Asexuality has not previously been observed in colonies of another major group of social insects, the termites, where the ubiquitous presence of both male and female workers and soldiers indicate that males play a critical role beyond that of reproduction.ResultsHere, we report asexual societies in a lineage of the termite Glyptotermes nakajimai. We investigated the composition of mature colonies from ten distinct populations in Japan, finding six asexual populations characterized by a lack of any males in the reproductive, soldier, and worker castes of their colonies, an absence of sperm in the spermathecae of their queens, and the development of unfertilized eggs at a level comparable to that for the development of fertilized eggs in sexual populations of this species. Phylogenetic analyses indicated a single evolutionary origin of the asexual populations, with divergence from sampled sexual populations occurring about 14 million years ago. Asexual colonies differ from sexual colonies in having a more uniform head size in their all-female soldier caste, and fewer soldiers in proportion to other individuals, suggesting increased defensive efficiencies arising from uniform soldier morphology. Such efficiencies may have contributed to the persistence and spread of the asexual lineage. Cooperative colony foundation by multiple queens, the single-site nesting life history common to both the asexual and sexual lineages, and the occasional development of eggs without fertilization even in the sexual lineage are traits likely to have been present in the ancestors of the asexual lineage that may have facilitated the transition to asexuality.ConclusionsOur findings demonstrate that completely asexual social lineages can evolve from mixed-sex termite societies, providing evidence that males are dispensable for the maintenance of advanced animal societies in which they previously played an active social role.

<b>New records of termites (Blattodea: Termitidae: Syntermitinae) from Colombia</b>

Eight species of termite from the Amazon and Orinoquia regions, belonging to four genera of the subfamily Syntermitinae, are recorded for the first time in Colombia. The species are Cornitermes cumulans (Kollar, 1832), Cornitermes pilosus Holmgren, 1906, Cornitermes ovatus Emerson, 1952, Cornitermes snyderi Emerson, 1952, Mapinguaritermes peruanus (Holmgren, 1906), Rhynchotermes amazonensis Constantini & Cancello, 2016, Rhynchotermes perarmatus (Snyder, 1925), and Uncitermes teevani (Emerson, 1925). Diagnostic characteristics and geographic distributions for the recorded species are provided, with detailed photographs of the soldier caste. The diversity and distribution of indigenous termite species in Colombia are documented.

Caste-biased genes in a subterranean termite are taxonomically restricted: implications for novel gene recruitment during termite caste evolution

The caste system of social insects presents a classic polyphenism in which widely divergent reproductive and non-reproductive phenotypes are expressed from the same genome. In termites, the sterile soldier caste is particularly divergent in phenotype and presumably evolved under selection for defensiveness. In this study, we use genomic phylostratigraphy to show that genes with soldier- and other caste-biased expression from the Eastern subterranean termite Reticulitermes flavipes are more taxonomically restricted on the tree of life than genes with no caste-biased expression. This pattern suggests that caste-biased genes are relatively young and implies past selection for novel gene recruitment during termite caste evolution. Moreover, a soldier-biased set of 74 genes contains a higher proportion of orphan genes with no known homology than does a nymph-biased set or any null gene sets. This again suggests that the termite caste—and soldiers in particular—makes disproportionate use of evolutionarily novel genes that are potentially recruited from non-coding regions of the genome. Given that Reticulitermes and most termite soldiers are sterile, any past selection for genetic novelty of this caste must have been indirect and mediated through reproducing relatives.

Brain investment under colony-level selection: soldier specialization in Eciton army ants (Formicidae: Dorylinae)

BackgroundIn eusocial animal colonies, individuals from different castes often play divergent behavioral roles and confront distinct cognitive demands. Neuroecology theory predicts variation in cognitive demands will correspond to differences in brain investment because brain tissue is energetically expensive. We hypothesized colony-level selection for efficient energy allocation will favor reduced brain investment for castes with reduced cognitive demands. Neotropical army ants (genus Eciton) have morphologically-based worker castes; the specialized soldiers have reduced behavioral repertoires. We asked whether Eciton worker brain size and brain architecture varied with body size, and predicted the specialized soldier caste would have reduced investment in brain tissue.ResultsEciton brain size generally increased with body size, but relative brain size (brain size/body size ratio) decreased sharply with body size. Soldiers were the largest-bodied workers, but their total brain volume overlapped extensively with other workers and was small relative to body size. Furthermore, soldier chemosensory antennal lobes and central-processing mushroom bodies were smaller relative to their brain size.ConclusionsThese patterns suggest colony-level selection on brain investment efficiency has led to adaptive adjustments in brain tissue allocation among Eciton worker castes, with reduced brain investment in the behaviorally specialized soldiers.